Process line for multi-recycling, low-energy and high-purity extraction of lithium

ABSTRACT

A process line for multi-recycling, low-energy and high-purity extraction of lithium in the present disclosure is intended to increase the purity and the concentration of lithium ions in produced solutions gradually through steps of adsorption/desorption ion exchange, extraction, impurity separation, agent separation and concentration during which extractive liquids are returned, recycled and processed in previous steps for fewer dosages of chemicals and fewest discharged effluents, lower manufacturing costs than existing techniques, low specific energy consumption and consumable loss, and high-purity products with lithium ions.

FIELD OF THE INVENTION

The present disclosure relates to a process line for extraction of lithium, particularly a process line for multi-recycling, low-energy and high-purity extraction of lithium.

BACKGROUND OF THE INVENTION

Lithium, a core chemical element of the modern electronic industry and a basic substance of the digital facility industry or the new-energy vehicle industry, is exploited from liquid lithium mineral resources mostly or solid lithium mineral resources.

The technology to extract lithium from liquid minerals is criticized for three drawbacks as follows: (1) high specific energy consumption for production of lithium through the electrodialysis device array or the high-pressure filtering membrane/tube array, each of which is an energy-intensive facility; (2) a great quantity of strong acids consumed and residual in effluents which should be processed before discharges; (3) poor selectivity and low separation efficiency of produced lithium which satisfies the general industrial standard and needs to be further processed in other energy-intensive or raw-material-intensive facilities for battery-grade lithium.

As one technical option which is neither low-cost nor environment-friendly currently, the technology to extract lithium from liquid minerals is not as good as the technology to extract lithium from solid minerals due to the competitive disadvantage in prices. However, scarcity and limited reserves of solid lithium ores are impelling the lithium battery material manufacturers to discover an alternative technology to exert lithium for lower energy consumption and fewer liquid minerals to be discharged. That is, the existing technology to extract lithium needs to be upgraded and broken through.

SUMMARY OF THE INVENTION

To settle the above problems, a process line for multi-recycling, low-energy and high-purity extraction of lithium in which the ion exchange tower, extraction facilities, separation membranes and technologies such as ion absorption, membrane separation and electrodialysis are integrated for extraction of lithium with the battery-grade purity at the low specific energy consumption is provided herein. As shown in the process line of the present disclosure, the cost of production and the level of environmental protection are optimized because of neither demand for a great quantity of strong acids nor discharges of effluents with strong acids. Additionally, a downsized process line for multi-recycling, low-energy and high-purity extraction of lithium in the present disclosure is a carborne facility with core units packed into a forty-foot equivalent unit (FEU). In the other hand, raw material solutions contain low-concentration lithium ions usually which are compatible with multiple foreign ions for productions of high-purity high-concentration solutions with lithium-bearing compounds, for example, lithium chloride solution, lithium hydroxide solution, etc.

A process line for multi-recycling, low-energy and high-purity extraction of lithium in the present disclosure comprises steps as follows:

-   -   Step 1: Raw material solutions are pretreated for productions of         precursor solutions with lithium ions, desorption agents and         foreign ions;     -   Step 2: Precursor solutions with lithium ions are processed for         the first impurity separation through which first extractive         liquids and second extractive liquids are produced wherein the         concentrations of foreign ions in the first extractive liquids         range from 0.1 to 30 ppm and the concentrations of foreign ions         in the second extractive liquids range from 60 to 6,000 ppm;     -   Step 3: The first extractive liquids are processed for         separations of desorption agents through which third extractive         liquids and fourth extractive liquids are produced wherein the         concentrations of lithium ions in the third extractive liquids         range from 1 to 150 ppm and the concentrations of lithium ions         in the fourth extractive liquids range from 250 to 2,500 ppm;     -   Step 4: The fourth extractive liquids are concentrated for         productions of fifth extractive liquids and sixth extractive         liquids wherein the concentrations of lithium ions in the fifth         extractive liquids range from 1 to 150 ppm and the         concentrations of lithium ions in the sixth extractive liquids         range from 2,500 to 20,000 ppm;     -   Step 5: The sixth extractive liquids are processed for the         second impurity separation through which seventh extractive         liquids and eighth extractive liquids are produced wherein the         concentrations of lithium ions in the seventh extractive liquids         range from 2,500 to 20,000 ppm (for solutions with         high-concentration high-purity lithium ions) and the         concentrations of foreign ions in the eighth extractive liquids         range from 60 to 6,000 ppm.

In the process line, pretreatment is defined as one of adsorption/desorption ion exchange, membrane separation or extraction.

In the process line, the desorption agents are hydrochloric acids or sulfuric acids with a concentration less than 0.5 mol/L.

In the process line, the second extractive liquids are returned and processed in step 1.

In the process line, the third extractive liquids adjusted for a proper concentration are returned and processed in step 1.

In the process line, the fifth extractive liquids adjusted for a proper concentration are returned and processed in step 1 and/or step 3.

In the process line, the eighth extractive liquids adjusted for a proper concentration are returned and processed in step 2.

In the process line, the seventh extractive liquids as high-purity materials are supplied to lithium battery material manufacturers or dried and dehydrated as battery-grade lithium-bearing powders.

In the process line, the seventh extractive liquids are further processed for productions of high-purity lithium hydroxide and by-products of acid solutions to be adjusted for a proper concentration and returned and processed in step 1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view for facility structure about a process line for multi-recycling, low-energy and high-purity extraction of lithium in an embodiment.

FIG. 2 is a flow chart about a process line for multi-recycling, low-energy and high-purity extraction of lithium in an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, which is a schematic view of facility structure about a process line for multi-recycling, low-energy and high-purity extraction of lithium in an embodiment with respect to “pretreatment” conducted in an ion exchange tower for adsorption/desorption ion exchanges. However, “pretreatment” in the process line is conducted, without limitation, by technical measures through which liquids with lithium ions mostly (the ratio of lithium ions to total metal ions is greater than 50%) are transformed, refined, filtrated or extracted from raw materials and the technical measures should be incorporated in the scope to be claimed for “pretreatment”.

Firstly, raw material solutions and liquid desorption agents are fed into an adsorption/desorption module 200 for adsorption/desorption ion exchanges of lithium ions through a raw material runner 101 and a desorption agent runner 102, respectively; then, desorption liquids and effluents are discharged from a desorption liquid runner 103 and an effluent runner 104, respectively. The desorption liquids through a desorption liquid runner 103 are fed into a first impurity separation module 300 for impurity separation during which first extractive liquids with fewer foreign ions and second extractive liquids with more foreign ions are produced and discharged from a first extractive liquid runner 105 and a second extractive liquid runner 106, respectively: the second extractive liquids through the second extractive liquid runner 106 are returned to the raw material runner 101 for adsorption/desorption ion exchanges of lithium ions again; the first extractive liquids through the first extractive liquid runner 105 are fed into a desorption agent separation module 400 for separations of desorption agents during which third extractive liquids with low-concentration lithium ions and fourth extractive liquids with high-concentration lithium ions are produced and discharged from a third extractive liquid runner 107 and a fourth extractive liquid runner 108, respectively. Moreover, the third extractive liquids adjusted for a proper concentration through the third extractive liquid runner 107 are returned to the desorption agent runner 102 for adsorption/desorption ion exchanges of lithium ions again; the fourth extractive liquids through the fourth extractive liquid runner 108 are fed into a concentration module 500 in which fifth extractive liquids with low-concentration lithium ions and sixth extractive liquids with high-concentration lithium ions are produced and discharged from a fifth extractive liquid runner 109 and a sixth extractive liquid runner 110, respectively: the fifth extractive liquids through the fifth extractive liquid runner 109 are either returned to the desorption agent separation module 400 or adjusted for a proper concentration and returned to the desorption agent runner 102 for adsorption/desorption ion exchanges of lithium ions again; the sixth extractive liquids through the sixth extractive liquid runner 110 are fed into the second impurity separation module 600 for impurity separations during which seventh extractive liquids with fewer foreign ions and eighth extractive liquids with more foreign ions are produced and discharged from a seventh extractive liquid runner 111 and an eighth extractive liquid runner 112, respectively: the eighth extractive liquids through the eighth extractive liquid runner 112 are returned to the first impurity separation module 300; the seventh extractive liquids with ultra-high-concentration lithium ions as high-purity materials are supplied to lithium battery material manufacturers or dried and dehydrated as battery-grade lithium-bearing powders to be transported and stored.

Referring to FIG. 2, which is a flow chart about a process line for multi-recycling, low-energy and high-purity extraction of lithium in an embodiment with steps as follows:

Step S201, absorptions of lithium ions: raw material solutions with lithium ions are fed into an ion exchange tower in which lithium ions are absorbed through manganese-bearing or titanium-bearing absorbents in the ion exchange tower;

Step S202, desorptions of lithium ions: lithium ions are desorbed through acid desorption agents for productions of desorption liquids;

Step S203, first impurity separations: impurities in desorption liquids are separated for productions of first extractive liquids and second extractive liquids wherein the concentrations of foreign ions in the first extractive liquids range from 0.1 to 30 ppm and the concentrations of foreign ions in the second extractive liquids, which are returned to the ion exchange tower in step S201, range from 60 to 6,000 ppm;

Step S204, separations of desorption agents: desorption agents in the first extractive liquids are separated for productions of third extractive liquids and fourth extractive liquids wherein the concentrations of lithium ions in the third extractive liquids, which are returned to the ion exchange tower in step S202, range from 1 to 150 ppm and the concentrations of lithium ions in the fourth extractive liquids range from 250 to 2,500 ppm;

Step S205, concentration: the fourth extractive liquids are concentrated for productions of fifth extractive liquids and sixth extractive liquids wherein (1) the concentrations of lithium ions in the fifth extractive liquids, which are returned to the ion exchange tower in step S202 and/or returned and processed for separations of desorption agents in step S204, range from 1 to 150 ppm; (2) the concentrations of lithium ions in the sixth extractive liquids range from 2,500 to 20,000 ppm;

Step S206, second impurity separations: impurities in the sixth extractive liquids are separated again for productions of seventh extractive liquids and eighth extractive liquids wherein (1) the concentrations of lithium ions and foreign ions in the seventh extractive liquids as high-purity materials supplied to lithium battery material manufacturers or dried as battery-grade lithium-bearing powders range from 2,500 to 20,000 ppm and from 0.1 to 30 ppm, respectively; (2) the concentrations of foreign ions in the eighth extractive liquids, which are adjusted for a proper concentration and returned and processed for first impurity separations in step S203, range from 60 to 6,000 ppm.

Referring to FIGS. 1 and 2, which illustrate a process line for multi-recycling, low-energy and high-purity extraction of lithium in another embodiment. As shown in steps S201 and S202, raw material solutions with lithium ions and low-concentration acid liquid desorption agents are fed into the adsorption/desorption module 200 for adsorption/desorption ion exchanges of lithium ions and productions of desorption liquids and effluents. In detail, the low-concentration acid liquid desorption agents are 0.5 mol/L hydrochloric acid liquids and the adsorption/desorption module 200 is a dynamic quick ion exchange tower in which 10˜60% of liquid desorption agents involve the ion exchange reaction. In the embodiment, the desorption liquids consist of 0.4 mol/L hydrochloric acids and 0.1 mol/L lithium chloride (LiCl) (with 700 ppm lithium ions) such that 20% of liquid desorption agents participate the ion exchange reaction but 80% are kept unused.

As shown in step S203, the desorption liquids should be fed into the first impurity separation module 300 in which impurities such as magnesium ions or other foreign ions in raw material solutions are separated for productions of the first extractive liquids with fewer foreign ions and the second extractive liquids with more foreign ions. In this regard, the first extractive liquids consist of 0.4 mol/L hydrochloric acids, 700 ppm lithium ions and 2 ppm magnesium ions roughly and the second extractive liquids consist of 0.4 mol/L hydrochloric acids, 700 ppm lithium ions and 200 ppm magnesium ions roughly. Then, the second extractive liquids still including lithium ions and returned are mixed with raw material solutions for adsorption/desorption ion exchanges of lithium ions again. In detail, the first impurity separation module 300 is specified as but not limited to a nano-filtration membrane separation device or a specific foreign ion adsorption device.

As shown in step S204, the first extractive liquids are fed into the desorption agent separation module 400 in which desorption agents, particularly acid liquid desorption agents unreacted during the ion exchange reaction, are separated and recycled for productions of the third extractive liquids with low-concentration lithium ions and the fourth extractive liquids with high-concentration lithium ions. In this regard, the third extractive liquids consist of 0.4 mol/L hydrochloric acids and 40 ppm lithium ions roughly and the fourth extractive liquids consist of 0.4 mol/L hydrochloric acids, 1500 ppm lithium ions and 4 ppm magnesium ions roughly. Then, the third extractive liquids in which concentrated hydrochloric acids or water is added are adjusted for a proper concentration and returned and mixed with the acid liquid desorption agents for adsorption/desorption ion exchanges of lithium ions again; the fourth extractive liquids in which lithium ions with a proper concentration are ensured are taken as intermediate products directly and added into another processing step, for example, 1,500 ppm LiCl serves as raw materials for production of lithium fluoride (LiF). In detail, the desorption agent separation module 400 is specified as but not limited to a molecular membrane device, a RO membrane device, an electrodialysis membrane device or an electrolytic bath.

As shown in step S205, the fourth extractive liquids are fed into the concentration module 500 in which the concentration reaction is conducted for recycling of higher-concentration lithium ions and productions of the fifth extractive liquids with low-concentration lithium ions and the sixth extractive liquids with high-concentration lithium ions. In detail, the fifth extractive liquids consist of 0.4 mol/L hydrochloric acids and 100 ppm lithium ions roughly and the sixth extractive liquids consist of 0.4 mol/L hydrochloric acids, 8,000 ppm lithium ions and 20 ppm magnesium ions roughly. The fifth extractive liquids are either returned to the desorption agent separation module 400 or adjusted for a proper concentration and returned to the adsorption/desorption module 200 for adsorption/desorption ion exchanges of lithium ions; the sixth extractive liquids with satisfactory lithium ions and foreign ions serve as intermediate products directly and are added into another processing step. In detail, the concentration module 500 is specified as but not limited to a molecular membrane device, a RO membrane device, an electrodialysis membrane device or an electrolytic bath.

In the concentration module 500, both lithium ions and foreign ions are concentrated. Accordingly, as shown in step S206, impurities should be separated in the second impurity separation module 600 for productions of the seventh extractive liquids with fewer foreign ions and the eighth extractive liquids with more foreign ions. In detail, the seventh extractive liquids consist of 0.4 mol/L hydrochloric acids, 8,000 ppm lithium ions and 5 ppm magnesium ions roughly and the eighth extractive liquids consist of 0.4 mol/L hydrochloric acids, 8,000 ppm lithium ions and 100 ppm magnesium ions roughly. Moreover, the eighth extractive liquids adjusted for a proper concentration are returned to the first impurity separation module 300 and the seventh extractive liquids with ultra-high-concentration lithium ions as high-purity materials are supplied to lithium battery material manufacturers or dried and dehydrated for removals of water and hydrochloric acids and refined as battery-grade LiCl powders. In detail, the second impurity separation module 600 is specified as but not limited to a nano-filtration membrane separation device or a specific foreign ion adsorption device.

Alternatively, the seventh extractive liquids are reprocessed for preparations of high-purity LiOH solutions and by-products such as high-purity and low/medium-concentration hydrochloric acid solutions mostly through an electrodialysis membrane device or an electrolytic bath. Then, the seventh extractive liquids adjusted for a proper concentration serve as acid liquid desorption agents which are returned to the adsorption/desorption module 200.

Furthermore, a process line for multi-recycling, low-energy and high-purity extraction of lithium in the present disclosure comprises, without limitation, the above modules and steps which can be adjusted for a particular order, addition of another step or deletion of a single or multiple steps as required.

For fewer desorption agents in desorption liquids, the measures in prior arts include an extension of the description reaction or a reduced excessive description-agent ratio through which the proportion of unreacted desorption agents is reduced. On the other hand, for a higher concentration of lithium ions in desorption liquids, the initial concentration of desorption agents for more lithium ions to be replaced in the ion exchange step should be higher than planned. However, the above two principles are contradictory to each other, for example, the conflict between an increased initial concentration of desorption agents and a reduced excessive description-agent ratio. Moreover, an increased concentration of desorption agents or an extension of the description reaction is criticized for the shortened service life of desorption agents, increased costs and poor production efficiency.

In summary, a process line for multi-recycling, low-energy and high-purity extraction of lithium relies on more than one step from which high-concentration lithium is extracted and acid liquid desorption agents matching a dynamic quick ion exchange process for ion exchanges within a short period of time and a longer service life of agents in contract to the prior arts. In these multiple steps for separations and concentrations, the concentrations of lithium ions in extractive liquids increase gradually but the concentrations of foreign ions decrease or are kept unchanged; extractive liquids in each step are recycled and returned to the previous step(s) as much as possible for fewer dosages of chemicals and fewest discharged effluents. Accordingly, with the specific energy consumption and the consumable loss lower than those of the prior arts, a process line for multi-recycling, low-energy and high-purity extraction of lithium is conductive to productions of compounds with high-purity lithium ions economically. 

What is claimed is:
 1. A process line for multi-recycling, low-energy and high-purity extraction of lithium, comprising steps: Step 1: Raw material solutions are pretreated for productions of precursor solutions with lithium ions, desorption agents and foreign ions; Step 2: Precursor solutions with lithium ions are processed for the first impurity separation through which first extractive liquids and second extractive liquids are produced wherein the concentrations of foreign ions in the first extractive liquids range from 0.1 to 30 ppm and the concentrations of foreign ions in the second extractive liquids range from 60 to 6,000 ppm; Step 3: The first extractive liquids are processed for separations of desorption agents through which third extractive liquids and fourth extractive liquids are produced wherein the concentrations of lithium ions in the third extractive liquids range from 1 to 150 ppm and the concentrations of lithium ions in the fourth extractive liquids range from 250 to 2,500 ppm; Step 4: The fourth extractive liquids are concentrated for productions of fifth extractive liquids and sixth extractive liquids wherein the concentrations of lithium ions in the fifth extractive liquids range from 1 to 150 ppm and the concentrations of lithium ions in the sixth extractive liquids range from 2,500 to 20,000 ppm; Step 5: The sixth extractive liquids are processed for the second impurity separation through which seventh extractive liquids and eighth extractive liquids are produced wherein the concentrations of lithium ions in the seventh extractive liquids range from 2,500 to 20,000 ppm (for solutions with high-concentration high-purity lithium ions) and the concentrations of foreign ions in the eighth extractive liquids range from 60 to 6,000 ppm.
 2. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein pretreatment is defined as one of adsorption/desorption ion exchange, membrane separation or extraction.
 3. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the desorption agents are hydrochloric acids with a concentration less than 0.5 mol/L.
 4. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the desorption agents are sulfuric acids.
 5. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the second extractive liquids are returned and processed in step
 1. 6. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the third extractive liquids adjusted for a proper concentration are returned and processed in step
 1. 7. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the fifth extractive liquids adjusted for a proper concentration are returned and processed in step 1 and/or step
 3. 8. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the eighth extractive liquids adjusted for a proper concentration are returned and processed in step
 2. 9. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the seventh extractive liquids as high-purity materials are supplied to lithium battery material manufacturers or dried and dehydrated as battery-grade lithium-bearing powders.
 10. The process line for multi-recycling, low-energy and high-purity extraction of lithium as claimed in claim 1, wherein the seventh extractive liquids are further processed for productions of high-purity lithium hydroxide and by-products of acid solutions to be adjusted for a proper concentration and returned and processed in step
 1. 